A variable resistance memory is a memory in which two-terminal variable resistance elements each having a variable resistance layer interposed between two electrodes are used as memory elements. In such a variable resistance memory, information writing and erasing are performed by using reversible changes in a variable resistance layer between a high-resistance state and a low-resistance state due to the history of voltage application between the electrodes. Even if the voltage between the two electrodes is cut off, the resistance state of the variable resistance layer is maintained. Accordingly, variable resistance memory is a type of nonvolatile memory.
Variable resistance elements are classified into several types based on the types of variable resistance layers and electrodes. For example, there are redox variable resistance elements that utilize movement of oxygen defects of transition metal oxides, ion-conducting variable resistance elements that utilize movement of metal ions or the like in the variable resistance layers.
For example, there are known ion-conducting variable resistance elements in which a thin amorphous silicon film is formed as a variable resistance layer on a silicon substrate doped at high concentration, and an ion source electrode having a metal ion source that can move in the variable resistance layer is formed on the variable resistance layer.